1. Field of the Invention
The present invention relates to an electric saw including a stroke arrangement which can be driven in a reciprocating manner and which has a tool receptacle in which a saw blade can be fixed. Further, the saw has a housing which extends along a stroke axis of the stroke arrangement and which forms, at its working tool-side end, an opening from which the stroke arrangement projects. The housing forms a receiving space in which there is arranged a motion transforming device which is formed, for example, by a gear unit, a motion transformer for transforming rotation into a reciprocating lateral motion, or by a combination of the two. The stroke arrangement is supported at the housing by a bearing element. The bearing element forms a sliding bearing for the stroke arrangement and is arranged between the motion transforming device and the housing opening. Further, an air flow can be directed to the housing opening in order to prevent dirt particles or dust particles from reaching the sliding bearing or the motion transforming device.
2. Description of the Prior Art
In jigsaws of the type mentioned above, dirt particles and dust particles can be prevented from penetrating into the housing via the working tool-side housing opening at least to a great extent by the available air flow. This minimizes the risk of increased wear or damage as a consequence of soiling of the sliding bearing or of the motion transforming device.
A sealing structure for application in a reciprocating saw is known from DE 199 21 988 A1. It has a chamber of the gear unit housing which is sealed by a dust seal and a rubber packing. A sliding bearing of a sliding block carrying the working tool and a motion transformer are accommodated in the chamber. An air flow arising as a result of an overpressure generated in the chamber by the sliding block exits recurrently from the chamber and past the dust seal provided at the working tool-side end of the chamber. Further, a seal holder with a felt ring is provided between the dust seal and a working tool-side housing opening. An air flow toward the housing opening, which is intended to minimize the entry of dust into the chamber through the dust seal, is provided at the side of the felt ring remote of the dust seal.
The known jigsaw is disadvantageous in that the resources for sealing the chamber and the additional production costs arising therefrom are relatively large. Further, because of a vacuum pressure which is recurrently built up in the chamber and by which air is sucked in via a valve arranged remote of the tool, there is a risk that air containing substantial dust will also be sucked in via the dust seal on the tool side. This risk exists in particular because the dust seal is stressed relatively severely by the air circulation exiting from the chamber, which leads to relatively rapid material fatigue. Accordingly, particles can enter through the dust seal into the chamber, where they cause increased wear on the sliding bearing and motion transformer.